Glow lamp



, April 17, 1934; s5 N ET AL 1,955,079

GLO W LAMP Filed July 8. 1950 INVENTORS v FRITZ MICHELSSEN BY FRITZ CH OTER ATTORNEY Patented Apr. 17, 1934 PATENT OFFICE.

GLOW LAMP Fritz Michelssen and Fritz Schriiter,

Berlin,

Germany, usignors to Teleiunken Geselisehai't iiir Drahtlose Telegraphie m. b. IL, Berlin, Germany, a corporation oi Germany Application July 8, 1930, Serial No. 468.406 In Germany July 10, 1929 2 Claims.

It has heretofore been known that a luminous column such as that produced from glow-discharge or gaseous-conduction lamps or tubes emits much more light in longitudinal direction than in right angles thereto. This is due to the fact that in longitudinal direction the light given oil by the individual ions becomes integrated. This property could be utilized for a great number of purposes, for instance, in picture telegraphy work, television and the phono-illm art. where such a glow-discharge lamp is employed for the object of converting electric impulses into light in a way free from siuggishness. However, when using glowdischarge lamps comprising electrodes having a form as heretofore usual, the problem of leading-in or supplying the current has been attended with certain difilculties, and these are to be obviated by the present invention.

In the case of picture telegraphy the form 01' construction illustrated in the accompanying drawing has proved advantageous, it being understood, of course, that this embodiment could be used also for many other purposes. The drawing shows by Fig. 1 a longitudinal cross-section through anode and cathode of the glow-discharge lamp, while Fig. 2 represents a transverse crosssection through Fig. 1 on the line 2-2 thereof and Fig. 3 represents a view similar to Fig. 2 but or a modified form of tube electrode construction.

Making specific reference to Figs. 1 and 2 of the drawing, the cathode K has the form oi a hollow cylinder of suitable cross-section and convenient length. and the outer wall and current- .lead L1 thereof is insulated or separated from the gas filling by a glass vessel G. Also, the anode A supplied with current through lead L2, insulated in a similar manner to lead L1, is separated from the cathode K. The entire assemblage is contained within a gas filled container or envelope C.

If the distance between anode and cathode and the pressure .01 the gas filling have been correctly'chosen, then, on switching in the current, the first glow discharge will occur in the part of the cathode capillary closest to the anode. As the current grows in value, the cathode glowlayer also will grow and finally extend as far as the points of the cathode most remote from the anode. Since an examination oi. the luminous column is possible only in the direction 01 the cylinder axis, the cathode glow becomes more intense when the current is large than when it is small.

Ifthe anode is designed in the form 01' a diaphragm, it is possible to allow the glow light to act through this diaphragm. However,so far as the modulation of the light at the rhythm of the electric impulses is concerned, this scheme involves an inconvenience. The luminous intensity coming to act from the dii'i'erent points of the 810w capillary is governed by the opening or aperture depending upon the cross-sectional area and the distance from the diaphragm. As the distance from the diaphragm increases, also the angle of aperture decreases. In such. an arrangement the glow-discharge lamp operates with a fairly large initial volume of light and with ,slow growth of luminous intensity as the current increases.

In order that the luminous variations corresponding. to the variations of the current may be made as large as possible, it is necessary to cause light to act also from the opening of the capillary opposite (or turned away from) the anode in the manner disclosed by this invention. The glow light due to smaller currents is formed in the vicinity of the anode and presents a small angle of aperture. But as the current grows, also the angle of aperture of fresh glow layers becomes larger, and the luminous intensity increases. The eilect of the integration of the light in iongitudinal direction of the capillary tube, and the increase in the aperture as the current increases become superposed and added to each other so that a better reproduction of modulation of the electric current by the glow-light is possible. A curve giving the inter-relationship between current and brightness presents a greater steepness when the glow issuing from the opening turned away from the anode comes to act than when it acts through the anode designed to serve as a diaphragm. 7

The same principle is applicable, 01 course, also to forms of construction as used, for instance, in recorder lamps employed in making speaking films. It is to be remembered that what is required in that case is not a punctii'orm, but rather alinear, conversion of electric current into light. The hollow cathode then no longer is a cylindrical capillary tube,.as just described, but the same rather presents the shape of a flattened ellipse in cross-section, as shown by Fig. 3. The outer wall is insulatedso that cathode glow is able to develop here also only in the inner space.

From the above description, it is, of course, obvious that many modifications and changes may be made in the structure therein disclosed without departing from the spirit and scope of the in-' vention, and we, therefore, believe ourselves to be entitled to make and use any and all modifications such as would readily suggest themselves to those skilled in the art to which the invention relates.

Having now described our invention, what we claim and desire to secure by Letters Patent is the following:

1. In a glow lamp construction, an elongated hollow cathode body haying a uniform ellipticalcross-sectional formation throughout its length, an anode arranged to cooperate with said cathode. and a layer of insulating material surrounding said cathode.

and cathode.

FRITZ BCI-IRCTER. FRITZ MICHELSSEN.

I l-L3 

